c
      subroutine actmov
c
c  this routine performs the active motion on
c  entity n.  The data is passed on to afact.
c
      include 'active.inc'
      include 'domain.inc'
c
c--local variables for bryosome problem-----------------
c
      integer i,npos,mshift,irad, nct
      double precision pi,theta0(6),dist,dth
      double precision cang,sang,rad,theta
c
c--save some variables for future reference------------
c
      save irad, mshift, rad, nct, pi, theta0, dth
c
c--initialize the saved variables--perform once only---
c
      npos = 120
      if (irad.eq.0) then
        irad = 1                                         
        rad = dist(tethx(1),tethy(1),tethx(2),tethy(2))
        mshift = npos/2
        pi = 4.0d0*datan(1.0d0)
        theta0(1) = (-pi/4.0d0)
        theta0(2) = (pi/12.0d0) - (pi/4.0d0)
        theta0(3) = (-pi/12.0d0) - (pi/4.0d0)
        theta0(4) = (5.0d0*pi/4.0d0)
        theta0(5) = (pi/12.0d0) + (5.0d0*pi/4.0d0)
        theta0(6) = (-pi/12.0d0) + (5.0d0*pi/4.0d0)
      endif
c
c--advance the time dependent saved variables only if 
c   this is the first call to actmov for a given time --
c
      if (nct.ne.nt) then
        nct = nt
        mshift = mod(mshift+1,npos)
        dth = mshift*pi/2.0/dble(npos)
      endif
c
c--using the entity label, determine the angle of the
c    cilia----------------------------------------------
c
      if (elab.le.3) then
        theta = theta0(elab) + dth
      else
        theta = theta0(elab) - dth
      endif
      cang   = dcos(theta)
      sang   = dsin(theta)
c
c--move the tether points by delta theta---------------
c----reset to the start if a sweep has been completed--
c
      do i=2,nels
        tethx(i) = (rad*dble(i-1)*cang) + tethx(1)
        tethy(i) = (rad*dble(i-1)*sang) + tethy(1)
      enddo
c
c--move the immersed boundary points to the start------
c----if a sweep has been completed---------------------
c
      if ( mshift .eq. 0 ) then
        do i=2,nels
          ibptx(i)  = tethx(i)
          ibpty(i)  = tethy(i)
        enddo
      endif
c
      return
      end     
c
c--------------------------------------------------------------
c
      subroutine getsrc (ntsrc)
c
c  user routine that specifies the sources
c
      implicit none
c
      include 'domain.inc'
      include 'sink.inc'
c
c  global variables
c
      integer ntsrc
c
c  insert local variable definitions here.
c  *** ALL VARIABLES MUST BE DECLARED ***
c
c  specify the location (xsourc,ysourc) and strength
c  of a source (src) here.
c
c  The user should be sure the number of sources and
c  sinks does not exceed the number declared in the
c  .ibis file
c
      ntsrc = 0
c
      return
      end